Well, I wouldn't say it doesn't need it. For slow-typists, it'd be easier to voice chat during combat, rather than hunt-and-peck to communicate, since this game doesn't support Macros (well, the icon-based Macros, like they did in City of Heroes). And during Space Combat, even fast typists will find their fingers occupied manuevering and blasting away, so voice chat can be very helpful there too.

However, voice chat would always be another option, use it or not. >_>

People in MMOs use Ventrilo for voice chat. Just look at WoW, they added the feature and no one uses it. It's a waste of development manpower to add the feature when everyone will just use vent anyway.